TICKLE SENSATION — TIME 
täte all that is heard (echolalia), or to mimic 
the movements of others (echokinesis), and 
so on. These impulses are closely allied to 
the working of the Imperative Idea (q. v.). 
The intelligence is not affected, and at times 
intense effort may overcome the morbid tic ; 
hut it is often a chronic and incurable dis¬ 
order. 
Irresistible motor habits are termed con¬ 
vulsive tics, and the others psychic tics ; while 
the more elaborate ones are termed co-ordi¬ 
nated tics. 
Tic douloureux is an acute Neuralgia 
(q. v. ) of the trigeminal or facial (fifth cranial) 
nerve. 
Literature : Noir, Etude sur les tics (1893). 
(j.j.) 
Tickle Sensation [ME. tiklen\ : Ger. 
Kitzel ; Er. chatouillement ; Ital. solletico, 
formicolio. A Touch Sensation (q. v.), whose 
conditions are still obscure. 
Tickling possibly includes a peculiar organic 
quality derived from the unstriped muscles 
that lie directly beneath the skin, and pos¬ 
sibly a circulatory quality (tingling and itch¬ 
ing : see Organic Sensation). Probably the 
muscular movement is wholly reflex, and the 
sense components in tickling are simply those 
of light and intermittent touches and tem¬ 
peratures, with which visual or other associa¬ 
tions are conjoined. The muscular reaction 
of laughter is intimately bound up with the 
sensation. 
Besides the well-localized tickle proper, 
described above, there is a sensation-complex, 
from rubbing and moulding the skin and 
muscles, especially in certain regions (e.g. the 
neck), which has very analogous, but more 
massive, reflex effects. This is also called 
‘ tickling,’ and is made use of in the games of 
children. It has never been analysed. 
Literature : Külpe, Outlines of Psychol., 
89, 147, 250; Sanford, Course in Exper. 
Psychol., expt. 31 ; Hall and Allin, The 
Psychol, of Tickling, &c., Amer. J. of Psychol., 
ix. 1897, 1. (E.B.T.-J.M.B.) 
Tiedemann, Dietrich. (1748-1803.) 
Born at Bremervörde and educated at Göttin¬ 
gen. In 1776 he became a teacher of ancient 
languages at the Collegium Carolinum in 
Cassel, in 1786 professor of philosophy and the 
Greek language at Marburg, where he died. 
Tilt-hoard: see Laboratory and Ap¬ 
paratus, III, B (c), (3). 
Timbre : [Lat. tympanum, a drum, through 
Er.]: Ger. Klangfarbe; Fr. timbre; Ital. 
tirnbro. The complex of overtones and noise 
that accompanies the Fundamental Tone 
(q. v.) of a musical note. 
It varies with the instrument, and thus 
enables us to recognize the source of the 
sound, as piano, harp, &c. It is sometimes 
termed clang-tint or quality (Helmholtz, Eng. 
trans., as below, Index, ‘ Quality ’) of a musical 
tone. It would seem better, however, to 
reserve the term quality for Pitch (q. v.). 
Literature : Helmholtz, Sensations of Tone, 
119; Sanford, Course in Exper. Psychol., 
expt. 90; Titchener, Exper. Psychol. (1901), 
expt. 8. (E.B.T.-J.M.B.) 
Time [Lat. tempus ; Gr. xp°vos] '• Ger. 
Zeit; Fr. temps’, Ital. tempo. The measur¬ 
able form of continuity and externality of 
parts in all real (empirical) process. Time is 
constituted of the complex of relations of dura¬ 
tion and succession in the experienced order 
of events. See Succession and Duration, 
and cf. Change. 
Time may be variously conceived, accord¬ 
ing to the point of view, as the order or 
arrangement of existences in these relations, 
as quantity or ‘ number ’ of changes relative 
.to order of succession, and, again, as the ideal 
‘ place ’ or medium in which these relations 
of duration and succession are found. These 
conceptions are general, applicable to an 
indefinite number of instances. But all times 
are commonly considered to be parts of one 
unlimited time. This one single time, how¬ 
ever, is neither an individual conception nor 
an ‘intuition,’ but an object to which the 
general conception of time is applicable in 
a special way. There is no ‘ intuition,’ i. e. 
perception, of ‘ pure ’ time, and the only 
way of representing it which is at all clear is 
by the imaginary synthesis of moving points 
or lines in space. 
All accounts of time agree in connecting 
it with change. A changeless content, like 
a mathematical relation or a Platonic idea 
or, in general, valid meaning or truth, is 
not in time. But though change is essen¬ 
tial to time, time is not the mere qualitative 
form of change. Nor is it mere succession or 
the mere abstract relation of succession. For 
succession to be temporal a relation of the 
terms is required such as to form a continuous 
and measurable series. The abstraction from 
the content of the relation of before and after 
in the continuity of a measurable process is 
temporal succession. The abstraction from 
the content of the total form of such a suc¬ 
cessive, continuous, and measurable process 
is time. Time is thus both continuous and 
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